op rochester



P. C. SEEL.

ANTISTATIC PHOTOGRAPHIE FILM.

Avrucmon mso nEc.31.|szu.

1,434,453 Patented Nov. 7, 1922.

WITNESS iNvENToR Paul (/'Seel,

ATTORNEY static Photographic 'very greatly minimized.

Patented Nov. 7, 1922.

UNITED STATES PATENT OFFICE.

PAUL c. smiL', or nccn'rscrnn, maw Yoan, sssroi'von 'ro msnm KomixcomrnNY,

F ROCHESTER, NEW YGRK,

n convenanten or NEW Yoan.

iirs'rnrrc rnofroonnrmo FILM.

Application filed December 3l, 1920. Serial No. 4591,353.

To all whom it may concern:

Be it known that I, PAUL C. Sani., a citizen of the 'United States ofAmerica, residin at Rochester, in the county of Monroe and State of NewYork, have invented certain newv `and useful Im rovenients in Antiv1551115, oi which the following is u ull, clear, and exactspecification;

Iliinvelition relates to photographic film. The rincipal object othisinvention is to prvieafilm having theusual qualities essential incommercial practice, which will also be so' constituted that themarkings due to electrical l discharges are prevented or Other objectswill hereinafter appear.

In the handling of sensitive photographic liii,lparticulaily that of thestandard type which includes a nitrocellulose support or base,characteristic line's or patches sometimes appear on development, diieto electric al discharges which are induced during such handli'n soas tofog the film. The prvention o this defect becomes commereially veryimportant in the motion picture field, particularly when making negativefilm strips. In this art the trouble is referred to as static. Undercertain conditions the movement of the film through the motion'picturecamere may cause it to be very injuriously affected unless certainprecautions are taken. While the defect appears'mo're strongly with sometypes of canieras than others and while it may be to a certain extentavoided by alterations in the 'camera or cumbersome attachments thereto,nevertheless, it is highly desirable to prevent the static by a properconstitution of the film, so that the latter may be employed in anycommercial camera without, any precautions being taken by the user.

I have discovered that film having unex pectedly strong vanti-staticproperties may be prepared by adding certain substances to thenitrocellulose film base or support. My invention is an improvement uponthe means disclosed in U. S. Patent No. 584,862, Eastman June 2Q 1897,British Patent No. 7501, Boult, of pr. 20, 1892, and German Patent No.69,231, Eastman Photographic Materials Coinpany,Ltd.. of May 16, 1893.

Tllesc patents indicate a useful Way of combatting static by adding oneor more of it andareta-in it in' the composition into which have foundthat they are incorporated. tlie1i.usefulness is very greatlyincreased'if certain organic ingredients be added to the `nitrocellulosebase, together with small amounts ot water. These organic substancesare, when incorporated in the film, inert toward the photographicallysensitive coatings and are also inert as far as any impairment of thestrength and'transparency of the film base is concerned. They arefurthermore of low volatility and conse qiiently remain in the filmbase. But most important of all they have a strong power of retainingwater, which is incorporated in the film base with them; and retainingit moreover without its impairing the transparency of the base. They,therefore, may bc called h vgroscopic. Whilemy invention is not confinedto the use ofgylcerin but includes analogous and homologous substances,nevertheless, because of its cheapness, I prefer this ingredient.

In the accompanying drawing the single figure is a sectional View on anexaggerated scale of a filin embodying my invention. In the drawing l isthe base or support and Q is the sensitive layer.

In carrying out one illustration of my in vention7 may incorporate inthe nitrocellulose solution or dope from which the film base is inode amixture of a suitable metallic salt, glycerin, and water, the preferredsalt being sodium hypophosph'ite. This salt is preferably present in theproportion of l t0 1% of the weight of the cellulose nitrate in thesolution. The glycerin 'is present in the proportion of 2i to 5% of thenitrate and the water is added in the proportion of 2l; to 5% of theiiitrate. The salt, glycerin, sind Water :ire all thoroughly mixedtogether before being added to the nitrocellulose solution or dope.

For instance, l. may add the above men- Iioned mixture of a salt,glycerin, and water chloride, stannous chloride, calcium alcohols havingVmonium nitrate,

to dope comprising A,100 arts of nitrocellulose, 200 to' 400 (say 9501;parts of acetone, 200 to 400 (say 250) parts of methyl alcohol, and 2Oto 200 (say 40) parts of fusel oil. lf desired, additional invredients,such as camphor may be added om 1 to 30 (Say 1D) parts. The ingredientsare of the commercial icind which have been purified to the pointthat isusually employed in this art, so that transparent lilms o the necessarym'mimum color are produced. Acetone or methyl alcohol 'may be used aloneor varying admiictures of these two v olatile solvents, or otherequivalent volatile solvents of nitrocellulosemay be employed. In placeof fusel oil other monohydroxy aliphatic from 4 to 5 carbon atoms may beemployed, such as the normal butyl alcohol and isobut l alcohol.

Other salts Whic 4may be substituted for sodium hyposulte include, butarenot necearilv limited to, the following:

chloride, magnesium chloride, sodium chloride, amA tassium thiocyanate,cal cium bromide, zinc chloride, lead nitrate, aluminum nitrate, zincbromide, barium bromide zinc nitrate, zinc salicylate, sodiumhyposulfite, V,magnesium acetate, l .ammonium citrate, magnesiumsulfate, bismuth subcarbonate, sodium formate. It may be noted thatthesesalts,\like the sodium hypophosphite, have a yconsiderable aifinity forsmall amounts of water and, therefore, are in u 1 sense hygroscopic.Moreover, they are inert when incorporated in the film base with respectto the usual photographic sensitive coatings that may beassociatedtherewith.

The dope containing my improved ingredients, when thoroughly mixed andliltered if desired, is flowed or deposited into thin sheets from whichthe volatile solvents escape, leaving a tough, flexible, transparentlilm base or support. On this support the usual sensitive photographiccoatings are applied in a well known manner. The resulting photographicfilm, when prepared for motion picture work, has all the usualqualities, and in addition prevents or very greatly minimizes anytendency toward static markings without special precautions. The filmbase and dope are covered in my codirisional application, Serial No.461,915, Iiled pr, 16, 1921.

lla ving thus described my invention, what l claim as new and desire tosecure by Letiers Patent is:

l. A photographic film comprising a sensitive coating and an anti-staticnitrocellulose support therefor, which contains an inert metallic salt,an inert hy'groscopic organic compound of low volatility and n'ntel' i?,A photographic [ilm comprising a senstvsotmg `lose support t yhypoposphite, glycerin and water,

7. AA:photographie-film comprising a sensitive coating and ananti-static nitrocellulose support therefor, which contains an inertmetallic salt, glycerin and water.

3. A. photographic film comprising a sensitive coating and ananti-static nitrocellulose support therefor, which contains an inerthygroseopic metallic salt, an inert organic compound of low volatilityand water.

4. A photographic film comprising a sensitive coating land ananti-static nitrocellu lose support therefor, which contains an inerthygroscopic metallic salt, glycerin and water.y t Y A5.'A photographicfilm comprising a sensitive coatingand an antistatic nitrocellulose sulport t erefor, which contains sodium vhypopA oihit, an inerthygroscopic organic componn w volatility and water.

4 6.,A-,photographic film comprising. senand amanti-staticnitrocelluerefor, which oo'ntainsVs'odium .sitiye coating and ananti-static nitrocellulose support therefor, which .contains an inertmetallic salt in an amount notlexceed ing 1% of the Weight ofthenitrocellulose, an inert hygroscoplc organic compound of low volatilityin an amount not exceeding 5% of the Weight of the nitrocellulose, an anamount of water not exceeding 5% of the weight of the nitrocellulose. A,

, 8. A vphot; ,`graphic,film comprising asen- 'sitive coating and ananti-static` nitrocellulose support therefor, which contains an inertmetallic salt in an 'amount not eieeeding 1% of the weight of .thenitrocellulose, glycerin in :in amountnot exceeding 5% of the weight ofthe nitrocellulose and water in an amount not exceeding 5% of the weight.of the nitrocellulose. Y

9. A photographic film comprising a sensitive coating and anantifstaticnitrocellulose support therefor, which contains an inert hygroscopicmetallic salt in an amount not exceeding 1% of the weight of thenitrocellulose, an inert hygroscopic organic compound of low volatilityin an amount not ex ceeding.5% of the weight of the nitrocclluv lose,and water in an amount not exceeding 5% of the weight of thenitrocellulose.

10. A photographic film comprising a sen sitive coating and ananti-static nitrocellulose support therefor, which contains an amount ofsodium hypophosphite not exneeding 1% of the weight of thenitroccllulose, an amount of glycerin not exceeding 5% of the weight ofthe nitrocellulose, and an amount of water not exceeding 5% of the`weight of the nitrocellulose. c

